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. Author manuscript; available in PMC: 2015 Jun 1.
Published in final edited form as: Methods Appl Fluoresc. 2014 Jun 1;2(2):10.1088/2050-6120/2/2/024010. doi: 10.1088/2050-6120/2/2/024010

Figure 3.

Figure 3

Schematic principle of the Orbital Tracking method using the piezo-scanner. (a) A fluorescent particle located at a distance δ and an angle φ0 from the focal spot is scanned along an orbit of radius R, generating a modulation in the intensity pattern along the orbit. Based on the values of phase and modulation of the intensity pattern the software calculates the position of the particle. (b) The calculated position of the particle is used as a feedback to correct the position of the scanner of an amount δ toward the direction π+φ0, so that the modulation of the intensity is minimized